Wash. Rev. Code § 53.34.170
In the acquisition, construction, reconstruction, improvement, extension, or betterment of any project or projects authorized under the provisions of this chapter any port district creating and establishing any such project or projects may have and exercise all of the powers heretofore or hereafter granted to port districts for corporate purposes and, in addition thereto, may acquire by gift or grant, lease, purchase, or condemnation any public and private property, franchises and property rights, including state, county, and school lands and property, and littoral and water rights whether or not any such property is then devoted to public or quasi public proprietary or governmental use: PROVIDED, That the court shall find that the proposed condemnation of any property already devoted to a public use is for a higher public use, and may by appropriate contracts with any city, county, or other political subdivision of the state, with the state and any department of the government of the state (hereinafter referred to collectively as public agencies), or with any department, instrumentality or agency of the United States, acquire title to or the use of existing roads, streets, parkways, avenues, or highways or the closing of any roads, streets, parkways, avenues, or highways as may be necessary or convenient to the acquisition, construction, or operation of any such project or projects under such terms and conditions as may be mutually agreed upon. All public agencies are authorized to enter into contracts with port districts for the aforesaid purposes.
RCW 53.34.170